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4-Wire Heated

  1. Warm engine until coolant temperature is 185-205°F (85-95°C). Disconnect oxygen sensor connector. See Fig 1 . Connect ohmmeter between heater terminals of oxygen sensor connector as specified in OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL IDENTIFICATION  table. This test checks resistance of oxygen sensor heater element.
    Fig 1: O2 Sensor Connector Terminal ID
    G90A17368Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  2. When oxygen sensor is at 68°F (20°C), resistance should be approximately 12 ohms (20 ohms on 3.0L models). If resistance is not within specification, replace oxygen sensor.
    CAUTION: DO NOT  apply battery voltage to oxygen sensor output terminals. Damage to oxygen sensor could result.
  3. Apply battery voltage to oxygen sensor heater terminals as specified in OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL IDENTIFICATION  table. This heats oxygen sensor heater element.
  4. Connect digital voltmeter between output terminals specified in OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL IDENTIFICATION  table. Repeatedly race engine and observe oxygen sensor output voltage. If oxygen sensor output voltage is not within 0.6-1.0 volt, replace oxygen sensor.
    OXYGEN SENSOR 4-WIRE CONNECTOR TERMINAL ID

    Application Heater Circuit Output Circuit
    Mirage 1.6L & Summit 3 & 4 1 & 2